• The underlying data structure is red-black tree
  • Insertion Order is not preserved
  • All elements inserted in the sorting order of keys
  • Duplicate keys are not allowed
  • Duplicates values are allowed
  • Homogeneous objects are allowed which implement comparable interface (Else class cast exception)
  • If we are implementing the comparator interface then objects need not be homogeneous or implement comparable interface
  • Wheather we are dependent on default natural sorting order or customized sorting order there are no restrictions for values.
  • Null keys not allowed in TreeMap


  • Map m = new TreeMap()
  • Map m = new TreeMap(Comparator c)
  • Map m = new TreeMap(SortedMap s)
  • Map m = new TreeMap(Collection c)


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